The Hidden Slowdown: AI Coding Assistants Reduce Developer Productivity Despite Perceived Gains

Groundbreaking research from METR challenges widespread claims about AI coding tool benefits, revealing that experienced developers actually took 19% longer to complete tasks with AI assistance, yet reported believing they were 20% faster. This striking perception-reality gap exposes how cognitive biases mislead both individual programmers and organizations into overestimating AI productivity gains. The findings underscore the critical need for objective performance measurement rather than subjective developer assessments when evaluating AI tool investments.